Field devices, in particular field devices which are utilized with sensors for measuring fill levels, limit levels and pressures, are often based on transit time measuring or run time measuring. In transit time measuring, the signal transit times or signal run times of radar pulses or of guided microwave pulses are determined. From these signal transit times the desired measured variable or measured value is determined.
Radar pulses are radar signals of a particular frequency and duration. The radar signals and the microwave signals belong to the field of high-frequency (HF) technology. Therein, as signals that are laying in the range of high-frequency technology, signals in the frequency range of up to 2 GHz are used as guided microwave signals, and signals in the range from 5 GHz-7 GHz and from 24 GHz to 28 GHz are used as radar signals.
The term conductor leadthrough is intended to refer to a connecting apparatus for connecting two conductors. A conductor can be an electrical conductor such as a cable, a coaxial line or coaxial conductor, a hollow conductor, a strip conductor or some other device that is suitable for transmitting signals on a desired path between two locations.
The measuring probes, in particular radar antennas and microwave probes respectively, often need to operate under harsh environmental conditions. In the chemical industry it can happen, for example, that fill levels of explosive materials have to be measured in containers.
For the purpose of carrying out measuring in such dangerous environments, sealed plug-type connections, in particular sealed-off coaxial HF plug-type connections, and conductor leadthroughs respectively are used, which prevent the electronics of the measuring devices, field devices and evaluation devices respectively from establishing contact with the explosive substances.
The region in which the feed material is located is distinct from the region in which the measuring electronic is located. The two regions constitute separate zones.
In the use of a fill level sensor, conductor leadthroughs or leadthroughs between the zones may be necessary, which conductor leadthroughs or leadthroughs, while letting electrical signals pass, nevertheless maintain the zone separation. A sealed-off conductor leadthrough can maintain zone separation.
For sealing-off line leadthroughs or conductor leadthroughs, glass leadthroughs or ceramics leadthroughs are employed. Due to their production costs, these leadthrough solutions on a glass base or on a ceramics base are, however, cost-intensive solutions.
There may be a need for a simpler solution for a conductor leadthrough.